Blade tension

[Rolf]

I posted this on the SSWWC forum also.

Blade tension is always a bit of a challenge, especially for those just entering the hobby. If someone created a device that clipped onto the blade and gave you a quantitative reading instead of pinging the blade would you buy it.? They say about a 1/8 deflection when tensioned properly, but me with my meat hooks can easily push that where someone with a light touch wouldn't.

What much would you be willing to pay for a gadget like that? Free is not an acceptable answer.

[OCtoolguy]

Good question. Maybe $20 or less. Not sure I'd ever use it though. 

[Sycamore67]

I do not think I would buy such a device.  I ping the blade and that works and my hands are large.

I have measured the tension on my band saw blades just a few times using a digital caliper.  I was very close to recommendations.  No I just see how far the blade deflects.

[Scrappile]

Nothing, would I pay.  I'm a "pinger" and if I had a gadget and used it I'd ping anyway,,, that's just my way.

[Bill WIlson]

Something like that might be useful for beginners, but I suspect that with a little experience, they would very quickly learn to do without it.

[MrsN]

I just use the ping method. I also teach my students to ping the blade to see if it is tight. I put the blade in with out tension and pluck it, it doesn't ping. then I put tension on the blade and pluck it, it pings nicely. I have them go back and forth a couple of times and they usually get the hang of it.

[JTTHECLOCKMAN]

I would put that idea in the same category as the hold down foot that comes with each scrollsaw. There should be a site where you could send those things to recycle them. They are the first thing that comes off. There is a blade tension device for bandsaw blades on the market but again experience puts them to bed too.  

[trackman]

I set up the tension level on my EX the way the factory manual said. Put blade in flip lever and start cutting. No need to ping or push. Same every time. 

[Fab4]

Hi Rolf:
Sounds like another addition that is really not needed
The less gadgets to play with the better - my opinion only
Fab4

[Rockytime]

I'm almost stone deaf but I like my blades very tight. In my mind's ear I like to imagine it as E above high C in the treble clef. Only time I ever break a blade is a #1 blade fed from the bottom. Sometimes when they look bent up like a pretzel they will break.

[RangerJay]

The "ping" method or the "1/8 inch" method are both fine for folks that are new to the hobby - or for those who are occasional scrollers - but if one really adopt the hobby then after a while you just "know" - the knowledge of "experience-gained-over-time" will do you for the rest of your life  - so - having said that I'm thinking a device that definitively tells you the tightness of the blade is probably helpful for those getting into the hobby - but if they stick with it - they will soon develop their own sense of what is the correct tension - and the "tension-measurement-device" is very likely to be posted on Kijiji ......

Jay

 

[JimErn]

5 hours ago, Scrappile said:

Nothing, would I pay.  I'm a "pinger" and if I had a gadget and used it I'd ping anyway,,, that's just my way.

Yep me too

Hell I do the math in my head, and use a calculator to check my math

[new2woodwrk]

Unfortunately I'm in the same boat - maybe a good idea on paper, but not in practice.

[WayneMahler]

My saw is set up so I don't really think about. I make changes as the project requires and just go  from there. Tweaking is always done on the fly so to speak. 

[davidg]

I think the instrument for this purpose would incorporate a strain gauge, https://www.omega.co.uk/prodinfo/straingauges.html but would perhaps be an expensive addition. If such a device could actually warn of imminent blade breakage during sawing (via. an audio-visual alarm perhaps), then that may be justification for the cost.

As an experiment to try and visually measure tension on the blades, I recently had the idea of attaching an inexpensive clip-on guitar tuner (Eno ET- 3000+) to my Hegner. This still requires the blade to be plucked of course, but it does mean that someone who has hearing problems or is wearing ear defenders can now see a measured representation of the note that the plucked blade produces. To attach the tuner to the scrollsaw, I first mounted a right angled metal bracket (available from most hardware/DIY stores) to the hold-down attachment holes near the upper arm bearing, then simply clipped the tuner device to this. I then placed a small plastic bag over the top of the tuner to keep dust away from the interface buttons. As others have hinted in this thread, I'm not sure if I'm going to use the tuner regularly, but I can say that the device/method appears to work for quantitative blade tensioning and gives me a second option if my hearing diminishes.

[Rolf]

Thanks Guys and Gals,  great feedback. !  I have always liked to dial something in to specific value.  But like most of you once I have a good feel for my tools I just do what I need to do with a minimum of fiddling.

The reason for my asking this. An analitical tool may be helpful.

I have learned something about my Hawk and probably any saw with the long arms. My normal small detail blade has been the Olson 2/0 R 28 TPI. It is slow cutting but very controllable. I figured that after 14 years I should be able to control a more aggressive blade.
Bought some Pegas 2/0 R MGT 15.4 TPI , they are a bit thinner an narrower than the Olson.
I noticed that the blade had a sideways wobble when running at my normal cutting speed. I have never noticed this before.
So I increased the tension beyond where it should be and yes I broke a few blades. Brought the tension back to where it should be and slowed the saw down until the wobble went away.
That worked and the the blades really cut very nicely.
This is where I wish I had access to one of the EX style saws and do a comparison. I am thinking that the long arms of the Hawk have so much mass that there is some sort of varying tension going on with arm flex? I do not see this effect with a bigger blade.
Or  I need to go through my saw for a thorough tuneup.

[Scrappile]

I have had trouble with the small Pegas 2/0 flat blades.  These just seem too flexible and tend to wonder on me.  Especially in harder wood.  I have tried them... but have not spent time trying different tensions and speeds. 

[SCROLLSAW703]

Mr. Rolf,

You're on the right trail, Sir. I have noticed the very same thing when it comes to variation of smaller blades. The only blades I use are Olson and Flyin Dutchman, and have fer years. With my BM 26, I can load an Olson #2/0 28 tpi, adjust the blade tension where I want it to be, run the blade 30 seconds or so and readjust the tension before I even begin cuttin'. I have found this method to work best for me, especially with smaller blades because it seems to take the initial stretch out of the blade, and allows for longer cuttin' time. 

On my CW - 40, which is a 16'' saw, I can put the same blade in it and tension it, and if I try to push the blade speed beyond half or better, the blade begins to vibrate like nobody's business. In my 26, hell, I've got the blade speed backed off to less'n half or more before the vibration will stop. 

With heavier blades, I can run my BM at any speed I need to. I ain't a speed cutter, so I've never had a call to cut any project above 3/4 on the variable speed. I have noticed, too, that contrary to what the recommendation charts say, I use the #2/0 blades cuttin' 1/2'' hardwood for some perty intricate details. You can have a look see at my fb page at the projects I work on.

Matter of fact, I just finished a Hereford bull head cut in 1/2'' white oak. I cut a good share of it with #1 blades, #0 blades, and #2/0 blades, and it was cut on my Hawk.

Sawdust703(brad)

[kmmcrafts]

This is a issue with the Hawks for sure when you use the small blades.. I like a faster running saw speed.. and with the Pegas.. I some times have troubles with the #3 .. The pegas blades are awesome blades but they are also very thin and flimsy for a lack of a better word.. I end up having to slow the speed down when cutting with a number three pegas..  I break pegas blades from time to time on the Hawks.. but very rarely do with a FD or Olsen blade.. 

This doesn't happen on my EX or my DeWalt.. I run the EX full speed.. but... remember.. full speed on this saw is a little more than 3/4 the way up on the Hawks.. unless it's the older Hawks.. as my old Hawk tops out at 1500spm.. same as the EX.. That said.. I've run my Dewalt full speed with the pegas blades in the 0/2 and no issues at all with the blade breaking or flexing..

I believe Randy (Hotshot) talked about this issue way back when he had the Hawk saw couple years ago..

This has never really been an issue for me because I very very rarely use a blade smaller than a #3 anyway.. unless it's a spiral then I use a FD 0/2 and never any issues.. but then I do slow the saw just a little with spirals anyway.. 

@Rolf If you have a camera and can video your saw running on the blade.. play it back in slow motion.. You'll really see the flex of the blade then..

[SCROLLSAW703]

Kevin, 

I may be mistaken, but the top blade speed for the BM 26 is 1750 cps. With that said, and havin' very little knowledge about the DeWalts or EX, I can safely say that over my years of experience, and the breeds of saws I have had experience with, blade speed has a lot to do with blade control, as I'm sure ya are familiar with. 

The difference in the three saws in my shop with different blades is the fact that two of'em are 16'' saws, and one is a 26'' saw. As Mr. Rolf mentioned, the mass of the length in the arms has some to do with it, in my ten cent opinion, as well as blade alignment and speed. Keepin' your saw fine tuned at all times is a necessity. Again, in my ten cent opinion. Regardless of the breed of the saw, or how new or how old it is.

Sawdust703(brad)

 

[kmmcrafts]

Hi Brad, Good to see you postin again, I'd been wondering about you and hoping you 're doing good and just making sawdust  

Yes the speed on my 1998 226 Ultra, my BM-26, and my DeWalt  all have the maximum 1750 SPM speed.. The Excalibur and the very old 1993 Hawk 220VS is maxed out at 1500 SPM ... All three of my Hawks will get that blade flex on high speed.. though it's worst on the larger two saws.. in part because they can run faster.. and.. the longer arms.. The Excalibur and the DeWalt have very short arms.. right at the front of the saw.. only about 4-5 inch long arms.. and the design is a rocking motion..rather than a straight up / down motion of the longer arm saw types.. which is why I stood and still stand by my theory that the short link arm saws such as the Excalibur, DeWalt and like saws cut faster.. I went round and round with a few on here in the last couple years about this subject.. many disagree.. yet many that have had and used both styles of saws agree that the Hawks cut slower than the others.. assume the Hengers are a slower cut too as with any of the longer armed saws.. 

You are very correct about keeping the saw in tune... and maintained.. it doesn't take much to get that massive arms to get the blade going all wonky.. just a dry bearing dragging ever so slightly in the connecting rod ( rod between motor and lower arm) really messed up my tune on my Hawk Ultra last year.. It took me a minute to figure out what was going on.. because I check all the "normal" things to look at.. finally I just took the whole thing apart.. those bearings the grease had dried up.. and was causing enough drag to mess up that blade motion.. 

Anyway, Good to see you scouting the forums and putting your 2 cents in.. 

[crupiea]

Too much thinking. 

Just get it fairly tight and cut on a piece of scrap real quick.  You should have decent control. If it is hard to stay on line, its too loose.  If you are scared of it being too tight, its too tight. 

Thats it. You really only need it to perform they way it is designed. 

I do think I have actually seen a little device that hooks onto a saw and you would plink the blade like a guitar string and it would register.  Then you would adjust it accordingly. I have heard the note should be a C but have yet to test it out.  

[SCROLLSAW703]

2 hours ago, kmmcrafts said:

Hi Brad, Good to see you postin again, I'd been wondering about you and hoping you 're doing good and just making sawdust  

Yes the speed on my 1998 226 Ultra, my BM-26, and my DeWalt  all have the maximum 1750 SPM speed.. The Excalibur and the very old 1993 Hawk 220VS is maxed out at 1500 SPM ... All three of my Hawks will get that blade flex on high speed.. though it's worst on the larger two saws.. in part because they can run faster.. and.. the longer arms.. The Excalibur and the DeWalt have very short arms.. right at the front of the saw.. only about 4-5 inch long arms.. and the design is a rocking motion..rather than a straight up / down motion of the longer arm saw types.. which is why I stood and still stand by my theory that the short link arm saws such as the Excalibur, DeWalt and like saws cut faster.. I went round and round with a few on here in the last couple years about this subject.. many disagree.. yet many that have had and used both styles of saws agree that the Hawks cut slower than the others.. assume the Hengers are a slower cut too as with any of the longer armed saws.. 

You are very correct about keeping the saw in tune... and maintained.. it doesn't take much to get that massive arms to get the blade going all wonky.. just a dry bearing dragging ever so slightly in the connecting rod ( rod between motor and lower arm) really messed up my tune on my Hawk Ultra last year.. It took me a minute to figure out what was going on.. because I check all the "normal" things to look at.. finally I just took the whole thing apart.. those bearings the grease had dried up.. and was causing enough drag to mess up that blade motion.. 

Anyway, Good to see you scouting the forums and putting your 2 cents in.. 

Thanks Mr. Kevin! The last 6 weeks has been in & out of the hospital.......Again. They installed a picc line in my left arm durin' one hospital stay to run antibiotics thru. Our Sawbones finally come around with the diagnosis of bacterial meningitis. She was pumpin' 4 different antibiotics thru me, and one oral for about 7 weeks. And I just finished up another round of antibiotics by IV. 10 days of it! Hopefully I'm startin to get back on my feet! I just don't get around many folks! To damn much of a chance of gettin somethin I don't want, brother!

I've learned with the Hawks, at the length the arms are, they ain't goin to cut anywhere near as fast as the shorter link saws, Mr. Kevin. There is no possible way it can be done! On the flip side of that coin, the Hawks may not cut AS FAST per say as yer yeller or grey breeds, BUT, THE PRECISION of the Hawk by far outsteps any saw I've ever used or seen on the market, in my opinion. For whatever that's worth, I reckon. 

I do know a couple fellers that run several board feet a week thru their Hawks, & will tell ya they won't own anything but a Hawk. Others gripe about'em on accounta they cut to slow.

Truthfully, experience can make a saw do anything the operator needs it to do. It's all in how the saw is set up, run, & tuned. 

Mr. Kevin, I appreciate your acknowledgment, brother! It's always good to hear what ya have to say about my ten cent opinion. Keep makin sawdust, my friend! 

Sawdust703 (brad)

[kmmcrafts]

32 minutes ago, SCROLLSAW703 said:

Thanks Mr. Kevin! The last 6 weeks has been in & out of the hospital.......Again. They installed a picc line in my left arm durin' one hospital stay to run antibiotics thru. Our Sawbones finally come around with the diagnosis of bacterial meningitis. She was pumpin' 4 different antibiotics thru me, and one oral for about 7 weeks. And I just finished up another round of antibiotics by IV. 10 days of it! Hopefully I'm startin to get back on my feet! I just don't get around many folks! To damn much of a chance of gettin somethin I don't want, brother!

I've learned with the Hawks, at the length the arms are, they ain't goin to cut anywhere near as fast as the shorter link saws, Mr. Kevin. There is no possible way it can be done! On the flip side of that coin, the Hawks may not cut AS FAST per say as yer yeller or grey breeds, BUT, THE PRECISION of the Hawk by far outsteps any saw I've ever used or seen on the market, in my opinion. For whatever that's worth, I reckon. 

I do know a couple fellers that run several board feet a week thru their Hawks, & will tell ya they won't own anything but a Hawk. Others gripe about'em on accounta they cut to slow.

Truthfully, experience can make a saw do anything the operator needs it to do. It's all in how the saw is set up, run, & tuned. 

Mr. Kevin, I appreciate your acknowledgment, brother! It's always good to hear what ya have to say about my ten cent opinion. Keep makin sawdust, my friend! 

Sawdust703 (brad)

Well dang Brad, I sure hope you get to feeling better and can get out and make some sawdust.. 

[Rolf]

I have been very busy but I have some fretwork to do for SSWWC. I took another hard look at my saw discovered that the the  upper arm pivot bolt had backed out a bit allowing the upper arm to move a bit side to side. I was sure I had checked that, but evidently not.  Snugging that up eliminated the side to side movement. Too snug and the arm gets a tad stiff. 

So Kevin I will follow your lead and When I get a chance will tear down my saw and replace all of the bearings. The connecting rod is new. but the arm pivots are the originals.

Also the rear tensioning wedge assembly is showing signs of wear. If I am reading my hour meter correctly I think I have at least 4K hours on this saw.